Improvement in steam-boilers



'UNITED STATES PATENT OFFICE.

kCHARLES H. HASVVELL, OF NEV YORK, N. Y.

IMPROVEMENT IN STEAM-BOILERS.

Specification forming part of Letters Patent No. 151,777, dated June 9,1874; application filed April 4, 1874.

CAsE B.

To all whom it may concern Be it known that I, CHARLES H. HAswELL, ofthe city, county, and State ot' New York, have invented a new and usefulImprovement in Steam-Boilers, of which the following is a specificationMy invention relates to steam-boilers having a steam-chimney, notablymarine-boilers, but others also; and it consists in retaining theboiler-shell between the outer shell or cylinder and the inner shell ofthe steam-jacket, and jointing it to the latter instead of cutting itout, as heretofore done, the said retained portion being perforated toallow a free circulation of the steam between the boiler proper and thesteam-chimney. The object of the invention is twofold, namely, tostrengthen the boiler and brace the chimney.

Figure l is a sectional elevation of so much of a boiler as is requiredto illustrate my invention. Fig. 2 is a plan view of Fig. l in verted.

Similar letters of reference indicate correspondin g parts.

A is the boiler-shell; B, the outer shell of the steam-chimney; C, theinner shell, which, at its lower end, connects with the ordinarysmoke-flue; D, the portion of the boiler-shell extending from the outershell of the steamchimney B to the inner shell C; and E, theperforations, to allow the steam to circulate freely between the boilerand the steam-chimney.

Hitherto it has been customary to remove the entire portion D of theboiler-shell, and it has been a great and entirely unnecessary cause ofweakness to the boiler, for, by extending it to the inner shell C, itsstrength to resist rupture is preserved directly in proportion to thewidth of the metal retained, and

the steam circulates just as well through the holes as if the wholespace was open. Besides preserving much of the strength against theinternal strain Vheretofore lost, the weight of the steam-chimney andsmoke-pipe on the boiler is not so injurious, because the boilershell issupported vertically by the inner shell of the steam-chimney, with whichit is connected, so that the injuries to the joint between the chimneyand the boiler-shell, by the rising and falling of the shell due to thevarying conditions of internal pressure and temperature when steam ison, and external pressure and temperature when it is on", are avoided.Moreover, the extension of' the boiler-shell beneath the steam-chimneyand up to and around the inner shell thereof serves as a brace to thelatter.

Having thus described my invention, I claim as new and desire to secureby Letters Patent- A steam-chimney having a perforated bottom formed byanextension of the boiler-shell beneath it, whereby the boiler andchimney are both strengthened, substantially as set forth.

CHAS. H. HASWELL. VVitnesses T. B. MosHER., ALEX. F. ROBERTS.

